The fine structure of the presumptive eye forming region of the diencephalon of eyed and genetically eyeless axolotls will be examined using scanning and transmission electron microscopy. These techniques will also be used to examine the relationships between cellular elements of the developing neural retina during outgrowth of the axons of retinal ganglion cells and of the diencephalon during their decussation. Retino-tectal connectivity will also be examined over a range of genetic diversity between graft and host cells, by means of homoplastic, heteroplastic, and xenoplastic eye or brain grafts in birds.